Frequency shape control of omni-directional wheelchair to increase user's comfort

Development of a Human-Friendly Omnidirectional Wheelchair with Safety, Comfort and Operability Using a Smart Interface

“…The OMW, which can act as an autonomous (Kitagawa et al, 2002), semi-autonomous (Kitagawa et al, 2001) or power assisted (Kitagawa et al, 2004) wheelchair is shown in Fig. 1, and its specifications are shown in Table 1.…”

“…When a first-order lag controller is used for the transformation from force to velocity (Kitagawa et al, 2004), a large jerk (derivative of acceleration) occurs if the input force changes suddenly. This jerk is considered a factor very significant to riding comfort.…”

“…Moreover, in this research the human model is used for studying vibration of the human body when it moves in a horizontal plane, while previous researchers have used a human model for studying the problem of vibration of the human body when it moves in a vertical direction. In author's laboratory, a holonomic Omni-directional Wheelchair (OMW) which can act as an autonomous (Kitagawa, Terashima et al, 2002), semi-autonomous (Kitagawa, Terashima et al, 2001) or power assisted (Kitagawa, Terashima et al, 2004) wheelchair has been developed. Because of its omni-directional movement, it is able to navigate smoothly in structured inner environments using range sensors for getting environment information.…”

“…(Kondo, et al 2008). In the power assisted mode, in the authors' laboratory (Kitagawa, Terashima et al, 2004) a six-axis force sensor is used for measuring the force applied by the attendant in two orthogonal axes, X and Y, and a rotational direction θ. This force is then changed to reference velocity V x , V y , and ω by using a first-order lag controller.…”

“…Nevertheless, when the system was tested by different attendants, a completely satisfactory result was not obtained by every attendant, since each operator has his or her own tendencies, and thus the parameters of the fuzzy inference system must be reasonably tuned to respond to the individual. Tuning the fuzzy inference system by trial and error was thus attempted and its results reported in (Kitagawa, Terashima et al, 2004). This was found to be a time-consuming process, leading to fatigue and boredom in the attendants.…”